1. Field of the Invention
The invention relates to wellhead constructions; and, more particularly, to an improved cable feed-through device for use in a well head.
2. Description of the Prior Art
Various arrangements are known in the art for passing electrical cable through a well head to the interior of a well head casing. In U.S. Pat. No. 3,437,149 to Cugini et al, a pressure resistant cable feed-through means is disclosed extending from outside a well head construction to within a well casing and passing through a pressure zone in the well head. Coupling means are provided at opposite ends of the cable feed-through means and conductors embedded in a dielectric material are molded within and protected by a rigid metal casing or shell. The feed-through means facilitates assembly of a well head and may be carried by hanger means adapted to be passed through a blow-out preventer.
The cable feed-through means of Cugini et al is molded as one complete unit and the entire unit must be replaced when such means wears out and/or breaks down.
In prior art cable feed-through devices, before Cugini et al, the conductor wires of the cable feed-through device were pushed together in use which tend to change their dielectric centers. This caused shorts and raised the possibility of electrocution of the operator. Further, gases escaped around the conductor wires and thus such means could not hold the well head pressure.
The advantages of the Cugini et al cable feed-through means reside primarily in the fact that, since it is molded as one unit, the dielectric centers of the conductor wires do not change. However, since it is a single molded unit. it must be tested prior to use in the field. Also, since it does not lend itself to variations in length, a significant number of differing lengths msut be kept in inventory. In case of breakdown, the entire unit must be replaced. There is thus a need for a cable feed-through means which retains the advantages of the cable feed-through means of Cugini et al but reduces the number of such devices which must be kept in inventory, permits quick and easy replacement at the well, and eliminates the need for pre-testing.